HDU 1686 Oulipo【主串中模式串个数（可重叠）】

Oulipo

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 11588    Accepted Submission(s): 4564

Problem Description

The French author Georges Perec (1936–1982) once wrote a book, La disparition, without the letter 'e'. He was a member of the Oulipo group. A quote from the book:

Tout avait Pair normal, mais tout s’affirmait faux. Tout avait Fair normal, d’abord, puis surgissait l’inhumain, l’affolant. Il aurait voulu savoir où s’articulait l’association qui l’unissait au roman : stir son tapis, assaillant à tout instant son imagination, l’intuition d’un tabou, la vision d’un mal obscur, d’un quoi vacant, d’un non-dit : la vision, l’avision d’un oubli commandant tout, où s’abolissait la raison : tout avait l’air normal mais…

Perec would probably have scored high (or rather, low) in the following contest. People are asked to write a perhaps even meaningful text on some subject with as few occurrences of a given “word” as possible. Our task is to provide the jury with a program that counts these occurrences, in order to obtain a ranking of the competitors. These competitors often write very long texts with nonsense meaning; a sequence of 500,000 consecutive 'T's is not unusual. And they never use spaces.

So we want to quickly find out how often a word, i.e., a given string, occurs in a text. More formally: given the alphabet {'A', 'B', 'C', …, 'Z'} and two finite strings over that alphabet, a word W and a text T, count the number of occurrences of W in T. All the consecutive characters of W must exactly match consecutive characters of T. Occurrences may overlap.

 

Input

The first line of the input file contains a single number: the number of test cases to follow. Each test case has the following format:

One line with the word W, a string over {'A', 'B', 'C', …, 'Z'}, with 1 ≤ |W| ≤ 10,000 (here |W| denotes the length of the string W).
One line with the text T, a string over {'A', 'B', 'C', …, 'Z'}, with |W| ≤ |T| ≤ 1,000,000.

 

Output

For every test case in the input file, the output should contain a single number, on a single line: the number of occurrences of the word W in the text T.

 

Sample Input

  
  

   
   3
BAPC
BAPC
AZA
AZAZAZA
VERDI
AVERDXIVYERDIAN
  
  

 

Sample Output

  
  

   
   1
3
0
  
  

 

next的含义：模式串与主串失配后模式串滑动； next博大精深！！！

EXKMP超时；

AC代码：

#include<cstdio>
#include<cstring>

const int MAXN=1e6+33;
char T[MAXN],S[MAXN]; int ne[MAXN],ans;

void Get_ne(char *T,int *ne,int L)
{
	ne[0]=-1; int i=0,j=-1;
	while(i<L)
	{
		if(j==-1||T[i]==T[j]) ne[++i]=++j;
		else j=ne[j];
	}
}
void KMP(char *S,char *T,int LT,int LS)
{
	int i=0,j=0;
	while(i<LS)
	{
		if(j==-1||S[i]==T[j]) ++i,++j;
		else {
		
			j=ne[j];
		} 
		if(j==LT) ans++;
	}
}
int main()
{
	int t;
	scanf("%d",&t);
	while(t--)
    {
    	scanf("%s %s",T,S);
    	int LT=strlen(T),LS=strlen(S);
    	ans=0;
    	Get_ne(T,ne,LT);
    	KMP(S,T,LT,LS);
    	printf("%d\n",ans);
	}
	return 0;
}